Unsymmetrical bidentate ligands of α-aminoaldimines leading to sterically controlled selectivity of geometrical isomerism in square planar coordinationCCDC reference numbers 682281, 683783–683791 (3c, 4a, 4c, 5b, 5c, 6c, 7a, 7c, 8cand 10c). For crystallographic data in CIF or other electronic format see DOI: 10.1039/b805674a

New α-aminoaldimines with the formula of Et2NCMe2CHNR (R = iPr, tBu, Ph) and their dichloro or diacetato complexes of Ni, Pd, Pt are prepared and structurally characterized. A nickel complex is in a distorted tetrahedral configuration, and the Pd and Pt complexes (4–6) are of square planar form. The α-aminoaldimines can chelate to the metal in a C2-unsymmetric bidentate motif through the hetero functionalities of amine and imine, which show comparable transinfluence. Square planar organometallic palladium derivatives bearing α-aminoaldimines, including Pd–methyl, Pd–acetyl, and Pd–(η2-acetylnorboryl) (7–10), are also synthesized. The latter two species are a result of CO-insertion into Pd–methyl complexes and ensuing norbornene-insertion, respectively. The geometrical isomerism is found in the transconfiguration in most studied cases. Such a stereoselectivity results from the thermodynamic stability governed predominantly by steric control. The stereoselectivity is also supported by DFT calculations. [ABSTRACT FROM AUTHOR]